Speed rock bit



Nov. 16, 1943. P. J. SWOFFORD 2,334,453

SPEED ROCK BIT Filed April :50, 1942 Patented Nov. 16, 1943 UNITEDSTATES PATENT OFFICE I sPEEi iifzi BIT" Peter J. Swofl'ord, Fort Worth,Tex.

Application April 30, 1942, Serial No. 441,185

1 Claim.- ('Cl. 255-72) This invention relates to rock bits, and moreparticularly to a speed rock bit for cable tools, Y

and has for one of its objects the production of a simple and eflicientbit which is so constructed as to drill an annular or ring-like socketleaving a central core, which core may be broken-01f and removed intactafter first removing the bit.

- A further object of this invention is the production of a simple andefficient hollow bit having a plurality of cutting teeth arranged inannular formation and having cutting faces tapering inwardly andlaterally from the outer face and lower edge of the bit to provide amaximum cutting action.

Other objects and advantages of the present invention will appearthroughout the following specification and claim.

In the drawing:

Figure 1 is a perspective view of the bit;

Figure 2 is a side elevational view, certain parts being shown invertical section;

Figure 3 is a bottom plan view of the bit illustrating the cutting teethat the bottom of the bit;

Figure 4 is an enlarged vertical sectional view taken on line 44 ofFigure 3.

By referring to the drawing, it will be seen that Ill designates thebody of the rock bit, which is provided with a tapering upper end l lhaving slotted vents l2 and the conventional upper end construction l3.The body Ill is provided with a central bore thereby defining a hollowbody which hollow body is preferably about eight feet in length. Thebody I is provided with spaced longitudinally extending slots ll nearthe lower end of the body to provide a, series of annularly arrangedteeth l5, preferably about two feet in length.

The lower cutting face of each tooth I5 is shaped to provide a centrallylocated outer cutting point I6, and the bottom edge of each tooth isinclined upwardly and rearwardly as indicated at H. The lower face ofeach tooth is also inclined rearwardly, upwardly and is also inclinedlaterally and inwardly from the center of the tooth toward the sides ofthe tooth as illustrated in detail in Figure 4 at l8.

In view of the fact that the teeth l5 are ar ranged annularly or in aring-like formation, it should be understood that as the bit operates,an annular socket will be cut in the rock or hard formation throughwhich the bit is operating for the length of the hollow body, therebyforming a core IS. The bit may then be withdrawn and a sand buckethaving rippin dogs at the tom may be lowered to grip the core l9 andbreak about eight feet long.

off the core 19 close to its bottom as the bucket is lifted. The core l9may then be brought out intact and this core will provide a log todemonstrate the type of formation through which the .bit has beenoperating.

By actual experiment it has been found that the present rock bit almostequals the speed of a rotary bit. It has been found that by drilling a22 inch hole, the cutting surface in the present bit is 1 /2 inches, orthree inches overall, leavin a core of approximately 19 inches indiameter in the center. As stated above, the body II! is provided with aplurality of spaced slots which run about two feet vertically of thebody, from the bottom edge thereof, the body being preferably The coreI: will be cut into the formation through which the bit is operating,and since the body is hollow, this core may extend for a considerabledistance upwardly into the body, and when the maximum distance isreached, the bit may be withdrawn and a suitable sand bucket may be usedas specified above for the purpose of removing the core intact. It hasbeen found by actual practice that the use of this bit speeds up theconventional cable tool drilling approximately 75%.

The structure of the bit as illustrated and described also facilitatesthe sharpening of the bit and it has been found advantageous-to place aform in the slots I4 with the nub on the end and by striking the ends ofthe bit by means .of a blow from a sledge-hammer while the bit is hot,the bit may be reformed in the proper size and with the proper cuttingsurfaces; Where many sharpenings are necessary, a portable emerystonemay be utilized having a proper angle to touch-up the cutting points ofthe bit.

It has been found by experience that in a rotary rig a well is oftenlost by passing up oil and going to salt water.

The present type of bit has been designed to fit the standard drillshaft and the teeth [5 are so constructed at theirlower ends so as toprovide a diamond point near its lowest outer edge and these cuttingfaces taper inwardly or back toward the core, thereby providing all ofthe various cutting points necessary. It has been found that it ispractically impossible for a bit of this type illustrated and describedto ricochet or to cause a crooked hole, as often happens when using thestandard tool.

It should be understood that certain detail changes in the constructionof the device may be employed without departing from the spirit of theinvention, so long as such changes fall within the scope of the appendedclaim.

Having described the invention, what is claimed is: a

A core bit of the class described comprising a cylindrical body having acentral bore, a plurality of spaced slots extending longitudinallyinward from one end of the body defining spaced cutting teeth, eachtooth being bevelled on its working face from the middle to eachadjacent 10 slot, each such bevel inclining away from the working raceradially inward toward the bore and circumierentlally toward eachadjacent slot whereby each tooth has a central radially extendingcutting edge inclined toward the central bore away from the extremity ofthe tooth, and a plurality of other cutting edges at varying angles withrespect to each other.

PETER J. SWOFFORD.

